package com.cristina.attention.utils;

import com.google.common.collect.Maps;
import org.apache.commons.beanutils.PropertyUtilsBean;
import org.springframework.cglib.beans.BeanGenerator;
import org.springframework.cglib.beans.BeanMap;

import java.beans.PropertyDescriptor;
import java.util.Map;

/**
 * 动态添加 Bean 对象
 *
 * @author by superman
 */
public class BeanDynamicAddUtil {

    public static Object getTarget(Object dest, Map<String, Object> addProperties) {
        // get property map.
        // access Bean properties with org.apache.commons.beanutils.PropertyUtils.
        // getPropertyDescriptors() method is used to obtain the properties of the class.
        // Retrieve the property descriptors for the specified bean, introspecting and caching them the first time a particular bean class is encountered.
        PropertyUtilsBean propertyUtilsBean = new PropertyUtilsBean();
        PropertyDescriptor[] descriptors = propertyUtilsBean.getPropertyDescriptors(dest);
        Map<String, Class> propertyMap = Maps.newHashMap();
        for (PropertyDescriptor d : descriptors) {
            if (!"class".equalsIgnoreCase(d.getName())) {
                propertyMap.put(d.getName(), d.getPropertyType());
            }
        }
        // add extra properties
        // 将需要动态添加的属性添加到 map 中
        addProperties.forEach((k, v) -> propertyMap.put(k, v.getClass()));
        // new dynamic bean
        DynamicBean dynamicBean = new DynamicBean(dest.getClass(), propertyMap);
        // add old value
        // dest 中自带的属性且 addProperties 没有覆盖 dest 中的属性. 将dest中的属性添加到 beanMap 对象中
        propertyMap.forEach((k, v) -> {
            try {
                // filter extra properties
                if (!addProperties.containsKey(k)) {
                    // getNestedProperty() 为指定的 bean 返回指定名称的（可能是嵌套的）属性的值，没有类型转换, 对象内嵌套对象
                    dynamicBean.setValue(k, propertyUtilsBean.getNestedProperty(dest, k));
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        });
        // add extra value
        // 需要添加的属性
        addProperties.forEach((k, v) -> {
            try {
                dynamicBean.setValue(k, v);
            } catch (Exception e) {
                e.printStackTrace();
            }
        });
        Object target = dynamicBean.getTarget();
        return target;

    }
}

class DynamicBean {

    /**
     * 目标对象
     */
    private Object target;

    /**
     * 属性集合
     */
    private BeanMap beanMap;

    public DynamicBean(Class superclass, Map<String, Class> propertyMap) {
        this.target = generateBean(superclass, propertyMap);
        this.beanMap = BeanMap.create(this.target);
    }

    /**
     * bean 添加属性和值
     *
     * @param property
     * @param value
     */
    public void setValue(String property, Object value) {
        beanMap.put(property, value);
    }

    /**
     * 获取属性值
     *
     * @param property
     * @return
     */
    public Object getValue(String property) {
        return beanMap.get(property);
    }

    /**
     * 获取对象
     *
     * @return
     */
    public Object getTarget() {
        return this.target;
    }


    /**
     * 根据属性生成对象
     *
     * @param superclass
     * @param propertyMap
     * @return
     */
    private Object generateBean(Class superclass, Map<String, Class> propertyMap) {
        BeanGenerator generator = new BeanGenerator();
        if (null != superclass) {
            generator.setSuperclass(superclass);
        }
        BeanGenerator.addProperties(generator, propertyMap);
        return generator.create();
    }

}
